{
"version": "2.2",
"instance": {
"buks20231215_8k.htm": {
"nsprefix": "buks",
"nsuri": "http://www.buks.com/20240315",
"dts": {
"schema": {
"local": [
"buks-20240315.xsd"
],
"remote": [
"http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd",
"http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd",
"http://www.xbrl.org/2003/xl-2003-12-31.xsd",
"http://www.xbrl.org/2003/xlink-2003-12-31.xsd",
"http://www.xbrl.org/2005/xbrldt-2005.xsd",
"http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd",
"http://www.xbrl.org/lrr/role/net-2009-12-16.xsd",
"https://www.xbrl.org/dtr/type/2020-01-21/types.xsd",
"https://www.xbrl.org/dtr/type/2022-03-31/types.xsd",
"https://xbrl.sec.gov/country/2023/country-2023.xsd",
"https://xbrl.sec.gov/currency/2023/currency-2023.xsd",
"https://xbrl.sec.gov/dei/2023/dei-2023.xsd",
"https://xbrl.sec.gov/exch/2023/exch-2023.xsd",
"https://xbrl.sec.gov/sic/2023/sic-2023.xsd",
"https://xbrl.sec.gov/stpr/2023/stpr-2023.xsd"
]
},
"definitionLink": {
"local": [
"buks-20240315_def.xml"
]
},
"labelLink": {
"local": [
"buks-20240315_lab.xml"
]
},
"presentationLink": {
"local": [
"buks-20240315_pre.xml"
]
},
"inline": {
"local": [
"buks20231215_8k.htm"
]
}
},
"keyStandard": 19,
"keyCustom": 0,
"axisStandard": 0,
"axisCustom": 0,
"memberStandard": 0,
"memberCustom": 0,
"hidden": {
"total": 2,
"http://xbrl.sec.gov/dei/2023": 2
},
"contextCount": 1,
"entityCount": 1,
"segmentCount": 0,
"elementCount": 23,
"unitCount": 0,
"baseTaxonomies": {
"http://xbrl.sec.gov/dei/2023": 19
},
"report": {
"R1": {
"role": "http://www.buks.com/20240315/role/statement-document-and-entity-information",
"longName": "000 - Document - Document And Entity Information",
"shortName": "Document And Entity Information",
"isDefault": "true",
"groupType": "document",
"subGroupType": "",
"menuCat": "Cover",
"order": "1",
"firstAnchor": {
"contextRef": "d20248K",
"name": "dei:EntityRegistrantName",
"unitRef": null,
"xsiNil": "false",
"lang": "en-US",
"decimals": null,
"ancestors": [
"div",
"body",
"html"
],
"reportCount": 1,
"baseRef": "buks20231215_8k.htm",
"first": true,
"unique": true
},
"uniqueAnchor": {
"contextRef": "d20248K",
"name": "dei:EntityRegistrantName",
"unitRef": null,
"xsiNil": "false",
"lang": "en-US",
"decimals": null,
"ancestors": [
"div",
"body",
"html"
],
"reportCount": 1,
"baseRef": "buks20231215_8k.htm",
"first": true,
"unique": true
}
}
},
"tag": {
"dei_AmendmentFlag": {
"xbrltype": "booleanItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "AmendmentFlag",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Amendment Flag",
"documentation": "Boolean flag that is true when the XBRL content amends previously-filed or accepted submission."
}
}
},
"auth_ref": [
]
},
"dei_CityAreaCode": {
"xbrltype": "normalizedStringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "CityAreaCode",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "City Area Code",
"documentation": "Area code of city"
}
}
},
"auth_ref": [
]
},
"dei_DocumentInformationLineItems": {
"xbrltype": "stringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "DocumentInformationLineItems",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Document Information [Line Items]",
"documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table."
}
}
},
"auth_ref": [
]
},
"dei_DocumentInformationTable": {
"xbrltype": "stringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "DocumentInformationTable",
"lang": {
"en-us": {
"role": {
"label": "Document Information [Table]",
"documentation": "Container to support the formal attachment of each official or unofficial, public or private document as part of a submission package."
}
}
},
"auth_ref": [
]
},
"dei_DocumentPeriodEndDate": {
"xbrltype": "dateItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "DocumentPeriodEndDate",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Document, Period End Date",
"documentation": "For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD."
}
}
},
"auth_ref": [
]
},
"dei_DocumentType": {
"xbrltype": "submissionTypeItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "DocumentType",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Document, Type",
"documentation": "The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'."
}
}
},
"auth_ref": [
]
},
"dei_EntityAddressAddressLine1": {
"xbrltype": "normalizedStringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityAddressAddressLine1",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Address, Address Line One",
"documentation": "Address Line 1 such as Attn, Building Name, Street Name"
}
}
},
"auth_ref": [
]
},
"dei_EntityAddressCityOrTown": {
"xbrltype": "normalizedStringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityAddressCityOrTown",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Address, City or Town",
"documentation": "Name of the City or Town"
}
}
},
"auth_ref": [
]
},
"dei_EntityAddressPostalZipCode": {
"xbrltype": "normalizedStringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityAddressPostalZipCode",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Address, Postal Zip Code",
"documentation": "Code for the postal or zip code"
}
}
},
"auth_ref": [
]
},
"dei_EntityAddressStateOrProvince": {
"xbrltype": "stateOrProvinceItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityAddressStateOrProvince",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Address, State or Province",
"documentation": "Name of the state or province."
}
}
},
"auth_ref": [
]
},
"dei_EntityCentralIndexKey": {
"xbrltype": "centralIndexKeyItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityCentralIndexKey",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Central Index Key",
"documentation": "A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK."
}
}
},
"auth_ref": [
"r0"
]
},
"dei_EntityDomain": {
"xbrltype": "domainItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityDomain",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity [Domain]",
"documentation": "All the names of the entities being reported upon in a document. Any legal structure used to conduct activities or to hold assets. Some examples of such structures are corporations, partnerships, limited liability companies, grantor trusts, and other trusts. This item does not include business and geographical segments which are included in the geographical or business segments domains."
}
}
},
"auth_ref": [
]
},
"dei_EntityEmergingGrowthCompany": {
"xbrltype": "booleanItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityEmergingGrowthCompany",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Emerging Growth Company",
"documentation": "Indicate if registrant meets the emerging growth company criteria."
}
}
},
"auth_ref": [
"r0"
]
},
"dei_EntityFileNumber": {
"xbrltype": "fileNumberItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityFileNumber",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, File Number",
"documentation": "Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen."
}
}
},
"auth_ref": [
]
},
"dei_EntityIncorporationStateCountryCode": {
"xbrltype": "edgarStateCountryItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityIncorporationStateCountryCode",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Incorporation, State or Country Code",
"documentation": "Two-character EDGAR code representing the state or country of incorporation."
}
}
},
"auth_ref": [
]
},
"dei_EntityRegistrantName": {
"xbrltype": "normalizedStringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityRegistrantName",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Registrant Name",
"documentation": "The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC."
}
}
},
"auth_ref": [
"r0"
]
},
"dei_EntityTaxIdentificationNumber": {
"xbrltype": "employerIdItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "EntityTaxIdentificationNumber",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Entity, Tax Identification Number",
"documentation": "The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS."
}
}
},
"auth_ref": [
"r0"
]
},
"dei_LegalEntityAxis": {
"xbrltype": "stringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "LegalEntityAxis",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Legal Entity [Axis]",
"documentation": "The set of legal entities associated with a report."
}
}
},
"auth_ref": [
]
},
"dei_LocalPhoneNumber": {
"xbrltype": "normalizedStringItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "LocalPhoneNumber",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Local Phone Number",
"documentation": "Local phone number for entity."
}
}
},
"auth_ref": [
]
},
"dei_PreCommencementIssuerTenderOffer": {
"xbrltype": "booleanItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "PreCommencementIssuerTenderOffer",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Pre-commencement Issuer Tender Offer",
"documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act."
}
}
},
"auth_ref": [
"r1"
]
},
"dei_PreCommencementTenderOffer": {
"xbrltype": "booleanItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "PreCommencementTenderOffer",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Pre-commencement Tender Offer",
"documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act."
}
}
},
"auth_ref": [
"r2"
]
},
"dei_SolicitingMaterial": {
"xbrltype": "booleanItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "SolicitingMaterial",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Soliciting Material",
"documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act."
}
}
},
"auth_ref": [
"r3"
]
},
"dei_WrittenCommunications": {
"xbrltype": "booleanItemType",
"nsuri": "http://xbrl.sec.gov/dei/2023",
"localname": "WrittenCommunications",
"presentation": [
"http://www.buks.com/20240315/role/statement-document-and-entity-information"
],
"lang": {
"en-us": {
"role": {
"label": "Written Communications",
"documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act."
}
}
},
"auth_ref": [
"r4"
]
}
}
}
},
"std_ref": {
"r0": {
"role": "http://www.xbrl.org/2003/role/presentationRef",
"Publisher": "SEC",
"Name": "Exchange Act",
"Number": "240",
"Section": "12",
"Subsection": "b-2"
},
"r1": {
"role": "http://www.xbrl.org/2003/role/presentationRef",
"Publisher": "SEC",
"Name": "Exchange Act",
"Number": "240",
"Section": "13e",
"Subsection": "4c"
},
"r2": {
"role": "http://www.xbrl.org/2003/role/presentationRef",
"Publisher": "SEC",
"Name": "Exchange Act",
"Number": "240",
"Section": "14d",
"Subsection": "2b"
},
"r3": {
"role": "http://www.xbrl.org/2003/role/presentationRef",
"Publisher": "SEC",
"Name": "Exchange Act",
"Section": "14a",
"Number": "240",
"Subsection": "12"
},
"r4": {
"role": "http://www.xbrl.org/2003/role/presentationRef",
"Publisher": "SEC",
"Name": "Securities Act",
"Number": "230",
"Section": "425"
}
}
} |
